The present invention relates in general to wireless communication systems, such as particular wireless local area networks, and is particularly directed to a controlled interference-avoidance, band-rejection filtering mechanism that is installable in a direct sequence spread spectrum communication device (e.g., a DSSS radio). This controlled filtering mechanism monitors a potentially interfering frequency-hopping spread spectrum transmitter, to identify one or more frequencies to which the FHSS transmitter is expected to hop during a communication interval of the DSSS communication device. Using this frequency-hopping information, the controlled filtering mechanism programs one or more spectral notches into the passband spectrum of the band-rejection filter, so as to exclude the potentially interfering frequencies from DSSS communication signals employed by the DSSS communication device during its communication interval.
Within the electromagnetic spectrum currently employed by wireless local area network (WLAN) devices there currently exists a potential bandwidth interference problem between relatively narrowband (1 Mbps) frequency hopping spread spectrum (FHSS) devices and wider bandwidth (11 Mbps) direct sequence spread spectrum (DSSS) devices. This problem essentially involves two incompatible wireless communication services attempting to use the same portion of the spectrum at the same time, due to the fact that a transmitting FHSS device will occasionally xe2x80x98hopxe2x80x99 into the passband of a DSSS device.
In accordance with the present invention, this potential spectrum usage collision problem is effectively obviated by installing a programmable band-rejection filter within the wider bandwidth DSSS communication device. No modification of the FHSS device is required. A filter control mechanism within an FHSS receiver monitors the operation of a potentially interfering FHSS transmitter, to identify one or more frequencies to which the FHSS transmitter is expected to hop during a communication interval employed by the DSSS communication device. Using this frequency-hopping information, the filter control mechanism programs one or more spectral notches into the passband characteristic of the band-rejection filter, so as to exclude the potentially interfering frequencies from being present in the DSSS communication signals of the DSSS communication device during its communication interval.